The Structured Approach, also known as structured design or functional decomposition, is a software development methodology that focuses on breaking down a system's processes into smaller, manageable units called functions or modules. The primary principle is to organize the program around the actions it performs. The system is viewed as a hierarchy of functions, where higher-level functions call lower-level ones to accomplish a task, directly aligning with the description of building programs from modules to meet functional requirements.

B. Model Approach: This is not a standard, formally defined software development methodology. The term is too ambiguous to be a correct answer.

C. Object-Oriented Approach: This approach is based on modeling the system as a collection of interacting objects, which encapsulate both data (attributes) and functions (methods), not just functions.

D. Transnational Approach: This is not a recognized term in software development methodologies and is irrelevant to the concepts of program design described.

1. Sommerville, I. (2011). Software Engineering (9th ed.). Pearson Education. In Chapter 2, Section 2.1.2, "Software engineering methods," structured methods are described as those that "use a functional viewpoint" and are based on "decomposing the system into a set of interacting functions."

2. Fairley, R. E. (1985). Software Engineering Concepts. McGraw-Hill. Chapter 5, "Design," details structured design (functional decomposition) as a primary method for deriving a modular program structure from a system's functional requirements (pp. 168-175).

3. University of Texas at Austin, Department of Computer Science. (n.d.). CS 373: Software Engineering - Notes on Design. Retrieved from course materials which describe Structured Analysis/Structured Design (SA/SD) as a top-down functional decomposition method focusing on processes and data flows between them.